Related Experiment Videos
D2O as a substitute for 3H2O, as a reference indicator in liver multiple-indicator dilution studies.
1Faculty of Pharmacy, University of Toronto, Ontario, Canada.
The American Journal of Physiology
|December 1, 1991
Summary
Deuterium oxide (D2O) is an ideal substitute for tritium water (3H2O) in multiple-indicator dilution studies of the rat liver. This method accurately assesses hepatic distribution and uptake processes, outperforming [14C]urea.
Area of Science:
- Physiology
- Biochemistry
- Pharmacokinetics
Background:
- The multiple-indicator dilution technique is crucial for appraising hepatic distribution and uptake.
- Accurate assessment requires simultaneous injection of vascular, extracellular, and cellular indicators alongside tracer substrates.
- Previous methods using tritium water (3H2O) or [14C]urea had limitations in simultaneous substrate and metabolite analysis or exhibited undesirable carriage effects.
Purpose of the Study:
- To develop and validate an assay for quantifying deuterium oxide (D2O) in plasma using Fourier transform infrared spectrometry.
- To evaluate D2O as a substitute for 3H2O in multiple-indicator dilution studies of the blood-perfused rat liver.
- To compare the efficacy of D2O with [14C]urea as a cellular indicator.
Main Methods:
- Development of a Fourier transform infrared spectrometry assay for D2O quantitation in plasma.
- Simultaneous injection of multiple indicators in a blood-perfused rat liver model: 51Cr-labeled red blood cells, 125I-labeled albumin, [14C]sucrose, 3H2O, and D2O.
- Analysis of indicator behavior in blood and liver tissue to determine accessible water spaces and distribution ratios.
Main Results:
- D2O demonstrated virtually identical behavior to 3H2O in both blood and liver.
- Accessible cellular water spaces were comparable for 3H2O (0.625 ml/g) and D2O (0.621 ml/g).
- Ratios of water spaces (cellular + interstitial / sinusoidal) were nearly identical for 3H2O (3.87) and D2O (3.89).
- D2O proved superior to [14C]urea, which showed a red blood cell carriage effect and less dispersion.
Conclusions:
- Deuterium oxide (D2O) is a validated and superior substitute for tritium water (3H2O) in multiple-indicator dilution studies.
- The developed Fourier transform infrared spectrometry assay enables accurate D2O quantification.
- D2O offers improved accuracy and reliability for assessing hepatic distribution and uptake compared to [14C]urea.